I hear a "screech" right after acceleration?

Just changed spark plugs(closed coil) @ 107,000, no problems except one looked a bit rusty....anyway afterwards she starts right up but as I was idling/reving in garage I hear a "screech" right after acceleration, it sounds almost like a short air burst. I stepped out and did accelerator by hand to try and determine where it comes from but hard to tell. I am NOT certain this came with the plug change as I don't usually idle/rev the car with the hood up and might have just missed it. Regardless I hope someone can tell me what might be happening here, how to fix and that I did no harm when I changed the plugs! Thanks ever so much